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Biomedical subjects

D L Bruce

Publications and source records attributed to D L Bruce.

At least 37 records · Page 2Linked to original sources
PubMed1980

Effect of halothane anesthesia on the human cortical visual evoked response.

The visual evoked response (VER) was monitored in eight women intraoperatively during anesthesia with halothane in oxygen administered via endotracheal tube. Control measurements were made prior to anesthetic induction in these unpremedicated patients. The latency of the positive peak designated P1 increased progressively from a mean of 113 +/- 10 (SD) msec in the awake state to the following values at indicated end-tidal halothane concentrations: 123 +/- 10 msec at 0.75 per cent; 130 +/- 9 msec at 0.90 per cent; 134 +/- 9 msec at 1.13 per cent. The differences among mean latency values at these anesthetic concentrations were insufficient to conclude that VER latency would be a useful monitor of anesthetic depth. However, significant effects were seen at clinical levels of halothane anesthesia, and the prolongation caused by anesthesia must be considered when using VERs to monitor central nervous system function during neurosurgery.

Adult↗
PubMed1980

A comparison of some indirect methods for predicting maximal oxygen uptake.

Nine male subjects took part in a comparative evaluation of four indirect tests commonly used for predicting maximum aerobic power (VO2 max). In three of these tests (involving cycling, stepping and walking) VO2 max was predicted from submaximal heart rates; in the fourth, VO2 max was predicted from the time taken to run 2 km. Additionally, VO2 max was predicted from the body fat content. All predicted values were compared with the VO2 max determined directly on a treadmill. The best estimates of VO2 max were provided by the timed run, and by the step test. Both heart rate measured during walking and body fat content proved totally inadequate for the reliable prediction of VO2 max. Taking into account such factors as cost, safety, and the time required for testing, it is concluded that the timed run is the submaximal test most suited to the indirect determination of VO2 max.

Adult↗
PubMed1980

Anesthesia, formed elements of the blood, and macrophages.

Anesthetics depress not only compact organs such as the brain and heart but also the diffuse array of single cells that comprise the formed elements of the blood and macrophages of the reticuloendothelial system (RES). The principal anesthetic effect is depression of contractile elements of these cells subserving the functions of phagocytosis, cell locomotion, and transvascular diapedesis. Marrow granulocyte production and in vitro lymphocyte transformation are also depressed. Effects on erythrocytes are limited to the membrane, which anesthetics render somewhat resistant to rupture. These anesthetic actions are of interest both to basic scientists concerned with structure and function of single cells and to clinicians caring for patients whose circulating and fixed formed elements are dysfunctional.

Anesthetics↗
PubMed1979

Incompatibility group P-1 bla+ plasmids do not increase penicillin resistance of Pseudomonas acidovorans.

Incompatibility group P-1 plasmids with the bla+ genotype were transferred from various Escherichia coli strains to Pseudomonas acidovorans strain 29. When resistance to ampicillin was used as the criterion, none of these plasmids appeared able to express their Bla+ phenotype in this host. When the plasmids were subsequently transferred back from these ampicillin-sensitive P. acdiovorans transcipients to E. coli strains, it was found that the Bla+ phenotype was again expressed. Although beta-lactamase was not detected in cultures of P. acidovorans transcipients, macroiodometric determinations of beta-lactamase activity made on broken cell suspensions revealed that beta-lactamase was indeed synthesized. It was concluded that P. acidovorans strain 29 allows expression of the bla gene within the cell but that this organism is unable to excrete the enzyme.

Ampicillin↗
PubMed1978

Elevation of creatine phosphokinase in young men after recreational exercise.

Twenty healthy male volunteers were divided into four groups for a period of recreational physical exercise. Standard blood chemistry determinations were made before exercise and on the two subsequent days. Creatine phosphokinase (CPK), SGOT, and lactic dehydrogenase levels were transiently elevated, but the change was considered significant only in the CPK level after certain types of exercise. Persons having these determinations performed should be questioned about recent physical exertion in the event of abnormal laboratory results.

Adult↗
PubMed1976

Effects of trace anaesthetic gases on behavioural performance of volunteers.

Nitrous oxide and halothane, in concentrations as low as 50 p.p.m. and 1.0 p.p.m. respectively, caused measurable decrements in performance in psychological tests in healthy male volunteers. Nitrous oxide alone caused similar effects. The functions apparently most sensitive to these low concentrations of anaesthetic agents were visual perception, immediate memory, and a combination of perception, cognition and motor responses required in a task of divided attention to simultaneous visual and auditory stimuli. These effects were absent in subjects exposed to nitrous oxide 25 p.p.m. and halothane 0.5 p.p.m.

Adult↗
PubMed1976

Halothane action on lymphocytes does not involve cyclic AMP.

Both theophylline and halothane inhibited transformation of human lymphocytes by phytohemagglutinin (PHA). Theophylline did not augment the inhibitory action of halothane and depressed PHA transformation of halothane-treated cells to the same extent as that of air-treated cells. Halothane- and air-treated lymphocytes, prior to PHA addition, had the same content of cyclic AMP. The addition of PHA to these cultures raised cyclic-AMP concentrations to the same extent in halothane- and air-treated lymphocytes. Halothane action on PHA-stimulated lymphocytes appears not to involve changes in cyclic nucleotide metabolism.

Cells, Cultured↗
PubMed1976

An audiovisual test of divided attention.

A description is given of an audiovisual reaction time task, performance of which was maximal after 15 min. practice and which lasted at this level for 1 wk. Sensitivity of the test was shown in an adverse effect of inhalation of traces of anesthetic gases. Comparing responses to auditory and visual stimuli, the control auditory reaction times were faster but were lengthened more in the presence of anesthetics than were the visual ones. This test may be useful in other studies of subtle depressant drug effects.

Anesthesia, Inhalation↗
PubMed1975

Halothane inhibition of rna and protein synthesis of PHA-treated human lymphocytes.

Cultured human lymphocytes treated with phytohemagglutinin (PAH) ahd higher rates of RNA and protein synthesis, as judged by incorporation of the labelled precursors -3H-URIDINE AND -14C-leucine, than did control cultures without PHA. These cultures were prepared from cells of the same donor, as were a third set of cultures which were equilibrated with 2 per cent halothane. The increased rates of RNA and protein synthesis six and 16 hours after PHA ADDITION WERE INHIBITED BY THE HALOTHANE, MODESTLY AT SIX HOURS AND STRIKINGLY AT 16 HOURS. These experiments provide further evidence that halothane prevents recruitment of resting cells into the active cycle of cell division.

Carbon Radioisotopes↗
PubMed1975

Psychological studies of human performance as affected by traces of enflurane and nitrous oxide.

Thirty human subjects were exposed for four hours to 500 ppm N-2O and 15 ppm enflurane in air and then, within five minutes, given a 35-minute battery of psychological tests. Performance of a divided-attention audiovisual task and a digit-span memory test were significantly decreased compared with control data following exposure to air. A tachistoscopic task, four tests from the Wechsler memory scale, and five others from the Wechsler Adult Intelligence Scale were unaffected. Thirty subjects exposed to 500 ppm N-2-O in air only scored significantly lower on the digit-span test only.

Anesthesia, Inhalation↗
PubMed1975

The anesthetic effect of air at atmospheric pressure.

Nitrogen has recognized narcotic potential at hyperbaric pressures. No narcotic effect of helium has been demonstrated at any pressure. We evaluated the effect of nitrogen in air at one atmosphere on human performance by comparing it with helium-oxygen using a four-alternative divided-attention task that requires rapid response to auditory and visual signal changes. There was a 9.3 per cent decrease in response time when subjects breathed helium-oxygen, a signigicant change (P less than 0.001). This change could not be ascribed to practice since the order of presentation of gases did not have a significant effect. It concluded that the nitrogen in ambient air slightly but measurable impairs human performance compared with a non-anesthetic gas such as helium.

Air↗
PubMed1975

A survey of anesthetic health hazards among dentists.

Measurable concentrations of waste anesthetic gases have been found in hospital dental operating rooms. A mail survey of 4,797 general dental practitioners and 2,642 oral surgeons indicated that 20.2% of the general practitioners and 74.8% of the oral surgeons had anesthetic exposures exceeding three hours per week. In the comparison of the health of individuals exposed or unexposed to inhalation anesthetics, there was a significant increase (78%) of spontaneous abortion in the spouses of exposed dentists and a significant increase (156%) in liver disease for exposed dentists. The implication of these findings and possible solutions are discussed.

Abortion, Spontaneous↗